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Say to yourself (and quickly) what color you SEE in each
word, NOT the word itself
This is called the Stroop Test. This
test is used in neuropsychological
evaluations to identify signs of
developing Alzheimer's,
dementia, and other cognitive
impairments.
Numeric Memory Test
• A. 3932
• B. 54923
• C. 439292
• D. 4812944
• E. 83231397
• F. 756391123
• G. 6732089420
• H. 43954973248
• I. 297562159364
Numeric Memory Test
1. What helped you or others remember larger
numbers?
1. What does this tell you about how your
memory works in your brain?
1. Is memory the same thing as learning?
How do we think and learn? The
Nervous System (Topic 6.5)
What is learning?
• What is learning?
• How does it occur in the brain?
• Does your brain change when you learn? If so,
how?
Neuroplasticity Video
After the video be able to answer:
• What is neuroplasticity?
• https://www.youtube.com/watch?v=iAzmyB9P
Ft4
Learning: Neuroplasticity
• New experiences result in neurons (brain
cells) connecting with each other
• Repetition of the experience or information
causes the pathway to strengthen
• When pathways are not used, they are pruned
(cut)
Neural Growth
Neural Pruning
• What is neural pruning?
• Between what ages does neural pruning occur?
• Why do you think neurons are pruned during this
period?
Parts of the Nervous System: 1)
Central (CNS) 2) Peripheral (PNS)
• Nervous System Composed of
–Brain
–Spinal Chord
–Nerves
Brain
Spinal Chord
Nerves
Spinal Cord – nerve pathways to and
from brain
Nerves – pathways of neurons to and
from brain
Label the Parts of Neuron Cell Structure
How do nerves
send signals?
• Nerves send signals
through the
individual neurons
that make up each
nerve.
• Signal goes from the
dendrite to the axon
(label the direction
with an arrow)
3 Functional Categories of Neurons:
Interneuron (Relay or Bipolar), Motor,
Sensory
Motor Neurons
• Send information from the brain to a muscle to
produce an action.
• Also called efferent neurons
Sensory Neurons
• Receive input from
the “outside” →
• To spinal cord →
• To brain stem →
• To area in brain
which processes the
information
• “Sense” is perceived
• Also called afferent
neurons
Interneurons
• Interneurons
transmit
information
between sensory
and motor neurons
• Have two “poles”
for receiving and
sending signals
(interneurons)
Reflex Arc Animation
• http://www.sumanasinc.com/webcontent/ani
mations/content/reflexarcs.html
Warm Up 11/30:
1) Draw a brief diagram of a neuron and label the
following: axon, dendrite, Schwan cell, nodes of
Ranvier, myelin sheath, axon terminal, cell/soma body,
nucleus, cytoplasm.
1) In what direction does a signal travel through a
neuron?
1) Draw a brief flow chart that shows the pathway of
nerve communication when you accidentally touch
something too hot (i.e. the reflex arc pathway). Make
sure to include the following terms: relay neuron,
spinal cord, motor nerve, sensory nerve, effector,
interneuron.
• Hand touches fire →
sensory input from
heat of fire to sensory
nerve → to spinal cord
→to area in brain
which processes info
→ sense is perceived
→ signal sent from
brain → to spinal cord
→ to motor nerves →
effector →muscles
contract
How do neurons (and nerves)
communicate?
• A) Chemical
signals →
neurotransmitter
s & synaptic
transmission
• B) Electrical
signals → action
potential
How do neurons send signals to each other? The Synapse
• Synapse = point of
connection between
two neurons
• Molecules called
neurotransmitters are
used to send chemical
signals between
neurons
• Neurotransmitters are
released from synaptic
vesicles
• The synaptic cleft is a
space between the
axon of cell 1 and the
dendrite of cell 2.
CELL 1
CELL 2
What is synaptic transmission?
• Signals are sent from the axon terminal of one neuron
(presynaptic cell) to the dendrite of a neighboring
neuron (postsynaptic cell) by sending
neurotransmitters across the synapse
• Neurotransmitters bind to receptor proteins on the
postsynaptic cell, which initiates transmission of signal
• Neurotransmitters only fit into specific receptor
proteins on a postsynaptic cell.
• Once the signal is sent, neurotransmitters are
reabsorbed by cell 1 to be used later.
Check in:
• How does the axon send
signals?
• How does the synapse send
signals?
Check in:
• How is a signal sent down one
neuron? An electrical action
potential
• How does one neuron send
signals to another neuron?
Chemical neurotransmitters
Animation: How and when does an signal
stop?
• http://learn.genetics.utah.edu/content/neuroscien
ce/crossingdivide/
• Some neurotransmitters are “stop signal” ; binding
to receptors stops transmission to the next cell
• The threshold for transmission is not reached
because not enough neurotransmitters are
crossing the synapse, and attaching to receptors.
What causes vesicles to release
neurotransmitters?
• The axon terminal also
contains voltage-gated
Ca2+ channels.
• “Voltage-gated” means
that they respond to
changes in voltage by
changing shape.
Steps to Synaptic Transmission
7) Neurotransmitters are
reabsorbed into the
presynaptic cell
7.
Neurotransmitters
are released from
receptors and get
reabsorbed back
into presynaptic
cell.
Summary of Action Potential & Synaptic Transmission
How do psychoactive drugs act in the brain?
Caffeine
Look at the picture carefully. Serotonin is a neurotransmitter.
The nerve pathways in your brain that it is found in are
related to feeling good. Why might Prozac work to reduce
depression?
• Dopamine is another neurotransmitter. It is in pathways
that are responsible for euphoria. Using the diagram,
explain why cocaine causes feelings of euphoria.
What is an action potential?
How does this electrical signal travel
from the dendrite to the axon
terminal within a single neuron?
What is the role of ions in neuron communication?
• Movement of a
signal through a
neuron depends on
the movement of
Na+ and K+ ions in
and out of the cell
• The movement of
ions results in a
difference in charge
within the neuron
What is an action potential?
• An action potential is the movement of an electrical
signal through a neuron
• The movement of an action potential down a
neuron is caused by the moving exchange of
sodium (Na+) and potassium (K+) ions moving in and
out of the cell.
• The movement of an action potential through a
neuron consists of 2 main stages : depolarization
and repolarization.
What is the
state of a
neuron when a
signal is not
being sent?
Positive
Outside,
Negative Inside
• This state is called
Resting Potential
Depolarization happens over and over again until it
the action potential reaches the end of the axon.
How does each segment of the neuron
go back to “resting potential”?
• Once the action potential passes, Na+ channels
close, and K+ channels open.
• K+ slowly moves out of the cell to restore the
negative charge inside of the neuron.
• Movement of Na+ out, and K+ in causes section of
axon to revert back to resting potential (negative
inside, positive outside).
Steps of Action Potential Moving Down a
Neuron
1) The axon membrane is at a resting potential of 70mV, and then rises to the threshold potential of 50mV, either due to a stimulus, or the binding of a
neurotransmitter at a synapse.
2) Them membrane depolarizes due to voltage-gated
Na+ channels opening and Na+ rapidly moving in.
3) The membrane repolarizes due to voltage-gated K+
channels opening and K+ slowly moving out.
4) The membrane returns to the resting potential due
to the eventual movement of Na+ back out, and K+
back into the cell.
Reference Site:
• http://webspace.ship.edu/cgboer/actionpot.h
tml
Membrane Potential & 4 Stages of
Moving Nerve Impulse
Nerve Impulse (Action Potential)
Animation
• http://highered.mheducation.com/sites/0072
495855/student_view0/chapter14/animation
__the_nerve_impulse.html
How does synaptic transmission propagate
the action potential for the next neuron?
• Binding of the neurotransmitters to
receptors on the postsynaptic
neuron causes Na+ gates to open,
allowing Na+ to enter the cell and
depolarize.
How does propagation differ between
myelinated and non-myelinated neurons?
Myelinated vs Non-myelinated Neurons
Giuliodori M J , and DiCarlo S E Advan in Physiology Edu
2004;28:80-81
©2004 by American Physiological Society
How does a nerve impulse travel faster down
myelinated vs. non-myelinated neurons? SALTATORY
CONDUCTION
How fast is Saltatory Conduction?
• The speed of nerve impulses varies enormously
in different types of neuron. The fastest travel at
about 250 mph, faster than a Formula 1 racing
car.
• For the impulse to travel quickly, the axon needs
to be thick and well insulated. This uses a lot of
space and energy, however, and is found only in
neurons that need to transfer information
urgently. For example, if you burn your fingers it
is important that your brain gets the message to
withdraw your hand very quickly.